Polyisocyanate polyaddition products

ABSTRACT

The polyisocyanate polyaddition products comprise hydrophobic compounds plus at least one further compound selected from the group consisting of: (i) organic, cyclic compounds having a molecular weight of from 200 to 3000 g/mol, (ii) salts of metals of transition groups I, II and/or VIII, (iii) organic and/or inorganic acid anhydrides, (iv) cyclic sulfonic esters and/or sulfones, (v) lactones, lactams and/or cyclic esters and/or (vi) α,β-unsaturated carboxylic acids, α,β-unsaturated carboxylic acid derivatives, α,β-unsaturated ketones and/or α,β-unsaturated aldehydes.

[0001] The present invention relates to polyisocyanate polyadditionproducts comprising hydrophobic compounds plus at least one furthercompound selected from the group consisting of: (i) organic, cycliccompounds having a molecular weight of from 200 to 3000 g/mol, (ii)salts of metals of transition groups I, II and/or VIII, (iii) organicand/or inorganic acid anhydrides, (iv) cyclic sulfonic esters and/orsulfones, (v) lactones, lactams and/or cyclic esters and/or (vi)α,β-unsaturated carboxylic acids, α,β-unsaturated carboxylic acidderivatives, α,β-unsaturated ketones and/or α,β-unsaturated aldehydes,preferably selected from the group consisting of: (i), (iii), (iv), (v)and/or (vi), particularly preferably selected from the group consistingof (iii), (iv) and/or (vi). Furthermore, the invention relates to aprocess for producing these polyisocyanate polyaddition products, inparticular mattresses or furniture upholstery and/or carpet backing. Theinvention also relates to the use of hydrophobic compounds for reducingthe formation and/or the content of primary amines in polyisocyanatepolyaddition products and/or for reducing the water uptake ofpolyisocyanate polyaddition products, in particular flexiblepolyurethane foams.

[0002] The production of polyisocyanate polyaddition products byreacting polyisocyanates with compounds which are reactive towardisocyanates in the presence of catalysts which accelerate the reactionof the substances which are reactive toward isocyanates with isocyanatesand, if desired, blowing agents, additives and/or auxiliaries isgenerally known.

[0003] Like other plastics, polyisocyanate polyaddition products aresubject to aging processes which generally, lead to a deterioration inthe use properties as time goes on. Important aging influences are, forexample, hydrolysis, photooxidation and thermal oxidation which lead torupture of bonds in the polymer chains. In the case of polyisocyanatepolyaddition products, for example polyurethanes, hereinafter alsoreferred to as PURs, especially the action of moisture and even more thecombination of moisture and elevated temperature results in hydrolyticcleavage of the urethane and urea bonds.

[0004] This cleavage is not only reflected in a significantdeterioration in the use properties but also leads to formation ofprimary aromatic amines, e.g. toluenediamine (TDA) anddiaminodiphenylmethane (MDA), or primary aliphatic amines such ashexamethylenediamine or isophoronediamine.

[0005] As experiments have found, amine formation is influenced by aseries of parameters. In particular, high temperatures above 80° C. incombination with high atmospheric humidity lead to hydrolytic cleavageof the urethane and urea bonds. Such conditions are of importance insome specific applications of flexible PUR foams.

[0006] A further parameter which has a significant influence on theformation of primary amines is the type and amount of catalysts used. Ashas been able to be shown in various experiments, the catalysts whichare present in polyurethane systems and are necessary for theurethanization and blowing reaction also catalyze the hydrolyticredissociation reaction to a considerable extent. The presence ofcatalysts is thus a critical precondition for the hydrolysis of theurethane and urea bonds. Furthermore, it has been able to be shown thatthe efficiency of the hydrolysis is highly dependent on the activity andthe type of catalyst, and also on whether the catalyst remains in thesystem or can migrate out of the material. In particular, tertiary aminecatalysts having reactive functional groups such as OH and NH₂considerably accelerate amine formation by lowering the activationenergy for the cleavage reaction. The functional groups result inincorporation of the catalysts into the PUR network formed and theproducts produced using them have the advantage of lower odor andfogging problems since the catalysts cannot escape by diffusion afterproduction of the PUR product. The same applies to formulationscomprising polyols which have been prepared using primary or secondaryamines as initiator molecules and thus have catalytically activecenters. Such polyols have been increasingly used in recent times. Inthe case of formulations which comprise such constituents and areexposed to particularly hot and humid conditions in specificapplications, the formation of primary amines as dissociation productscannot be ruled out. In contrast, in the case of foams produced usingamine catalysts which contain no functional groups capable of beingbuilt into the structure, the catalysts are generally given off only ashort time after manufacture or during aging of the foam. In the case ofsuch foams, hot and humid conditions lead to significantly lower aminecontents.

[0007] As compounds which reduce the aromatic amine content of flexiblepolyurethane foams, U.S. Pat. No. 4,211,847, GB 1 565 124 and DE-A 29 46625 make use of sterically hindered cycloaliphatic monoisocyanates andmonothioisocyanates. Owing to their steric hindrance and their lowerreactivity compared to aromatic isocyanates, these isocyanates react toonly a slight extent during the foaming reaction, so that freeisocyanate is available for reaction with any aromatic amines presentafter the foaming reaction is complete. Disadvantages of these knownteachings are that the compounds mentioned are relatively expensive and,especially the two last-named compounds, also participate at leastpartially in the urethanization reaction despite their steric hindranceand do not react only after the foaming reaction with aromatic amineformed. In addition, these isocyanates tend to migrate out of thefinished foam because of their low vapor pressure and thus pose afurther health hazard due to the occurrence of free isocyanate.

[0008] DE-A 42 32 420 discloses the use of α,β-unsaturated estercarboxylates for producing polyurethane foams which have an improvedcompressive strength and elongation at break. In that document, salts ofα,β-unsaturated ester carboxylates are used as catalysts for theNCO/water reaction. In an aside, it is stated that the compounds are,due to the presence of olefinic double bonds adjacent to the carboxylategroups, capable of addition of amino groups which are formed during theslow aging of the foam. A disadvantage of these compounds is theircatalytic action which has an adverse effect on the foaming reaction. Acatalytic action of additives for reducing the amine contents offinished PUR foams is, however, not desirable since this leads, asdescribed above, to further and accelerated formation of primary amines.

[0009] Hydrolysis inhibitors for polyurethanes containing ester groupsare described in DE-A 23 31 796, FR 1 550 562 and GB 1 014 974. Theincrease in the hydrolysis resistance of the PUR products is usuallybased on an improvement in the mechanical properties after storage underhot and humid conditions. DE-A 23 31 796 describes the addition of epoxycompounds in order to avoid hydrolysis of the ester groups in PURproducts. For the same purpose, FR 1 550 562 claims alkyl carbonates andGB 1 014 974 claims carbodiimides in combination with a, compoundcontaining enol groups.

[0010] DD 238 992 describes epoxidized synthetic products such astriglycerides, alkyl epoxystearates, etc., and epoxidized naturalproducts such as soya oil as hydrolysis inhibitors for polyurethaneelastomers. However, the improvement in the hydrolysis resistance(increased hardness, tensile strength and elongation at break) isrestricted to polyurethane elastomers containing polyesters as polyolcomponent. DD 298 246 claims a polyol component for producingnoncellular polyurethane moldings having an improved hydrolysisresistance. The improvement in the hydrolysis resistance is achievedhere by addition of fatty amines.

[0011] A similar reaction mixture is claimed in DE-A 3 443 341. Theimprovement in the elongation at break of possibly cellularpolyurethanes is achieved here by means of a mixture of an inorganicfiller, a metal salt of a fatty acid and a hydrophobicizing agent suchas a fatty acid amide, fatty alcohol or a natural or synthetic wax.

[0012] GB 2 313 128 discloses castor oil and derivatives and alsopolyols based on polybutadiene and saturated hydrocarbons (>C₁₀) forincreasing the resistance of polyurethanes to discoloration. It is alsopossible to use hydrophobic compounds without OH groups, for exampleolefins, paraffins and also animal and vegetable oils.

[0013] U.S. Pat. No. 5,549,841 claims a process for producing flexiblePUR foams having an improved compressive set for use in a tropical orsubtropical climate. This improvement is achieved by the use of polyolshaving a variable ethylene oxide content or a variable ethylene oxideend cap in combination with polymer polyols. The polymer polyolcomprises a vinyl polymer dispersion in a polyoxyalkylene base polyol.

[0014] EP-A 672 698 describes a process for producing polyurethanes byaddition of reaction products of polyalkylenepolyamines and natural fatsor oils. The foams produced using these products are largelyclosed-celled and therefore have a rigid foam character. Suchformulations are unsuitable for flexible foam applications.

[0015] A further document in which hydrophobic PUR foams are describedis EP-A 933. The foams produced with addition of fatty acids, fatty acidesters, adducts of fatty acids and EO/PO and also fatty acid amides havea high absorption capability in respect of, oil and possiblyhalogen-containing, hydrophobic compounds.

[0016] WO 99/00428 discloses flexible polyurethane foams which areproduced using hydroxylated polydienes.

[0017] It is an object of the present invention to modify polyisocyanatepolyaddition products, in particular polyurethane foams, in such a waythat the hydrolytic cleavage of urethane and urea bonds and thus, inparticular, the formation of aromatic amines is prevented or at leastreduced. The compounds should be inexpensive and readily available andshould be able to display their effect in the finished foam withoutfurther after-treatment. In addition, they should affect the foamproperties as little as possible.

[0018] We have found that this object is achieved by the polyisocyanatepolyaddition products described at the outset and the use of thehydrophobic compounds likewise described at the outset.

[0019] It has been found that the extent of hydrolytic redissociation ofurethane and urea bonds is dependent to a considerable degree on thepenetration of moisture into the foam matrix. It was thus necessary tofind additives which hinder the penetration of moisture, especially infoams which are exposed to hot and humid conditions. These additivesshould have no significant effect on the foaming reaction and theproperties of the foams.

[0020] The penetration of moisture into the foam matrix was able to beinfluenced by the degree of hydrophilicity or hydrophobicity of thefoams. It was found that, because of its water-repellent properties, ahydrophobic foam takes up less moisture than a hydrophilic foam. Theproblem described could accordingly be solved by increasing thehydrophobicity of the foams. Surprisingly, it was found that thesetechnical teachings according to the present invention not only enablethe penetration of water into, in particular, the flexible polyurethanefoam to be prevented but also enable the formation of primary amines tobe reduced.

[0021] The hydrophobic compounds used according to the present inventionare preferably employed in the generally known processes for producingpolyisocyanate polyaddition products, preferably polyurethanes which maycontain isocyanurate and/or urea structures, particularly preferablyflexible polyurethane foams. The present invention therefore alsoprovides a process for producing flexible polyurethane foams having theproperties according to the present invention in respect of water uptakeand/or water adsorption by producing the flexible polyurethane foam inthe presence of the hydrophobic compounds used according to the presentinvention.

[0022] The hydrophobic compounds used according to the present inventionpreferably contain groups which are reactive toward isocyanates, morepreferably from 2 to 4 reactive groups, in particular hydroxyl groups.

[0023] Preferred hydrophobic compounds have a molecular weight of from500 to 8000 g/mol and have at least one continuous carbon framework,i.e. a carbon framework connected by means of carbon-carbon bonds,having at least 8, preferably at least 10, carbon atoms.

[0024] The hydrophobic compounds used are therefore preferably reactionproducts of castor oil with alkylene oxides, epoxidized fatty acidesters, low molecular weight hydroxy-functional polyolefins preferablyhaving a molecular weight from 500 to 8000 g/mol and/or oleochemicalpolyols based on a C₉-C₂₂-fatty acid and prepared by ring opening ofepoxidized triglycerides.

[0025] In particular, it is possible to use modified, where the termmodified refers, for example, to ring-opened fatty acid esters, orunmodified fatty acid esters, oils, in particular vegetable oils, and/orpolyolefins, for example:

[0026] oleochemical polyols, e.g. triglycerides, based on a C₉-C₂₂-fattyacid and prepared, for example, by ring opening of epoxidized fatty acidesters, for example triglycerides, and preferably having a hydroxylnumber (OHN) of from 50 to 300 mg KOH/g, where the epoxy content can bevaried from 0% to 10% depending on the completeness of ring opening;

[0027] fatty acid esters, preferably epoxidized fatty acid esters,preferably having a hydroxyl number (OHN) of from 30 to 500 mg KOH/g,particularly preferably from 100 to 200 mg KOH/g, preferably based on aC₉-C₂₂-fatty acid, e.g. prepared by transesterification of oleochemicalpolyols with C₁-C₃₀-alkanols, e.g. alkyl epoxystearates, alkylepoxytallates, alkyl epoxytetrahydrophthalates, alkyl oleates, dialkyladipates, dialkyl sebacates, di(methylcyclohexyl) phthalate,dicyclohexyl phthalate, diisotridecyl phthalate, hexyl oleylcetylphthalate, di(oleylcetyl) phthalate, dioctyl adipate, diisodecyladipate, dibutyl sebacate, dioctyl sebacate, isobutyl stearate, the2-ethylhexyl ester of epoxidized soya oil, isobutyl esters of fattyacids, the isobutyl ester of tallow acid, 2-ethylhexyl stearate and/ortetrahydrofurfuryl oleate;

[0028] reaction products of natural vegetable oils, e.g. castor oil,linseed oil and/or soya oil, with ethylene oxide and/or propylene oxide,preferably propylene oxide, advantageously having an OHN of from 50 to200, particularly preferably from 80 to 90, mg KOH/g and/or

[0029] low molecular weight polyolefins, preferably having a molecularweight of from 500 to 8000 g/mol, which are preferablyhydroxy-functionalized at both ends and/or have an epoxidized isopreneunit at one or both ends.

[0030] Replacement of part of the polyol component, for example in theproduction of flexible polyurethane foams, by the hydrophobic compoundsdescribed enables the hydrophobicity of the foams to be increased sothat the penetration of moisture is significantly inhibited. This is atremendous advantage for, in particular, foams which are exposed to hotand humid conditions (hot steam disinfection or in future sterilizationof hospital mattresses, hot steam cleaning of upholstered furniture andcarpets). In the case of foams which have been produced using suchpolyols, the entry of moisture is inhibited to such a degree that theoccurrence of hydrolytic cleavage of urethane and urea bonds under hotand humid conditions is significantly reduced.

[0031] The formation of primary aromatic amines such as toluenediamineor diaminodiphenylmethane associated with this cleavage reaction islikewise significantly reduced by this measure. The stabilizing actionof the polyols used according to the present invention is advantageouslybased on a prevention of the formation of primary amines, while theaddition of other additives, e.g. the abovementioned sterically hinderedisocyanates, results in only primary amine which has already been formedbeing chemically bound. The hydrophobic compounds used according to thepresent invention do not pose a health hazard and can be easilyincorporated into the polyol component because of their goodcompatibility with the constituents of the polyol component. Thehydrophobic compounds used according to the present invention counterboth a deterioration in the mechanical properties, particularly whenexposed to hot and humid conditions, and also the formation of primaryamines, in particular primary aromatic amines, for example 2,2′-,2,4′-and/or 4,4′-MDA and/or 2,4- and/or 2,6-TDA.

[0032] The use of oleochemical polyols, in particular, gives open-celledfoams. Varying the proportion of these polyols allows the open cellcontent of PUR foams to be set in a targeted manner.

[0033] The use of the hydrophobic compounds described makes it possibleto obtain foams which consist in large part of natural, i.e.regenerating, raw materials. Since the production of molded PUR foamsand slabstock foams is increasingly looked at from an ecologicalperspective, finished products containing a relatively high proportionof recyclable components should be produced in future so as to conserveresources.

[0034] To produce the polyisocyanate polyaddition products, thehydrophobic compounds are preferably used in an amount of from 0.2 to upto 100.0% by weight, based on the weight of all the isocyanate-reactivecompounds employed.

[0035] To produce the polyisocyanate polyaddition products, it is alsoadvantageous to use (i) organic, cyclic compounds having a molecularweight of from 200 to 3000 g/mol, preferably from 200 to 1300 g/mol,hereinafter also referred to as “macrocycles”.

[0036] As a result of the use of the macrocycles, the macrocycles formcomplexes with tertiary amines which have been used as catalysts in theproduction of the polyisocyanate polyaddition products, in particular inthe finished polyisocyanate polyaddition product, and the tertiaryamines in the complex with the macrocycles can no longer display theircatalytic activity, i.e. they are blocked. Since the complexed aminecatalysts in the finished polyisocyanate polyaddition products are nolonger capable of catalyzing the abovementioned hydrolyticredissociation of urethane and urea bonds, the macrocycles counter botha deterioration in the mechanical properties, in particular on exposureto hot and humid conditions, and also the formation of primary amines,in particular primary aromatic amines, for example 2,2′-, 2,4′- and/or4,4′-MDA and/or 2,4- and/or 2,6-TDA. Furthermore, the formation ofcomplexes of the macrocycles used according to the present inventionwith primary amines, for example primary aromatic amines, can hindermigration or extraction of these amines from the polyisocyanatepolyaddition product. Migration or extraction of the amine catalysts,too, from the product is hindered by such complexation. The resultingreduction in odor and fogging problems is reinforced, in particular, bythe additives used according to the present invention being able to beat least partially incorporated into the polyurethane network due to thepresence of OH groups. The inclusion of primary and/or tertiary aminesby the macrocycles which have been fixed in this way leads to the aminesbeing immobilized in the foam matrix.

[0037] Macrocycles, e.g. cyclodextrins, are capable of the inclusion ofwater molecules as well as amines, which further reduces the occurrenceof hydrolytic cleavage reactions and thus additionally counters theformation of primary amines.

[0038] As macrocycles, it is possible to use generally known compounds,for example cyclodextrins, resorcinarenes, cyclophanes and/orcyclocalixarenes, each of which may be in modified form.

[0039] Such cyclodextrins, which may also have a branched structure, arementioned in, for example, U.S. Pat. No. 5,063,251, column 2, lines 55to 63, and DE-A 1 96 14 441, page 2, lines 46 and 47. Suitablecyclocalixarenes are described in U.S. Pat. No. 4,642,362, column 2,line 34 to column 7, line 68.

[0040] Preference is given to using α-cyclodextrin, β-cyclodextrin,y-cyclodextrin, reaction products of these cyclodextrins with alkyleneoxides, 4-tert-butylcalix[4]arene, 4-tert-butylcalix-[6]arene,4-tert-butylcalix[8]arene, 4-sulfocalix[4]arene, 4-sulfocalix[6]arene,4-sulfocalix[8]arene, C-methylcalix[4]resorcinarene,C-undecylcalix[4]resorcinarene, tetra-N-pentylcalix[4]resorcinareneand/or [2.2]paracyclophane, particularly preferably β-cyclodextrin,4-tert-butylcalix[6]arene, 4-sulfocalix[6]arene and/or[2.2]paracyclophane.

[0041] The macrocycles can be used in the A and/or B components or inthe constituents of these components, preferably in the isocyanatecomponent in order to avoid complexation of the amine catalysts whichare customarily present in the A component before the polyurethaneproduct has been produced. If the macrocycles are not soluble in eitherthe A component or the B component, they are dispersed in powder form inone of the two components and subsequently processed in this form.

[0042] To produce the polyisocyanate polyaddition products, themacrocycles are preferably used in an amount of from 0.2 to 5% byweight, based on the weight of the compounds which are reactive towardisocyanates.

[0043] Furthermore, (ii) salts of metals of transition groups I, IIand/or VIII, hereinafter also referred to generally as “metal salts”,are also advantageously used for producing the polyisocyanatepolyaddition products. For the purposes of the present invention, theterms “salts of metals” or “metal salts” also include the cations of themetals specified in complexed form.

[0044] As a result of the use of the metal salts, the metal ions formcomplexes with tertiary amines used as catalysts in the production ofthe polyisocyanate polyaddition products, and the tertiary amines in thecomplex with the metals can no longer display their catalytic activity,i.e. they are blocked. Since the complexed amine catalysts in thefinished polyisocyanate polyaddition products are no longer capable ofcatalyzing the abovementioned hydrolytic redissociation of urethane andurea bonds, the metal salts counter both a deterioration in themechanical properties, in particular on exposure to hot and humidconditions, and also the formation of primary amines, in particularprimary aromatic amines, for example 2,2′-, 2,4′-and/or 4,4′-MDA and/or2,4- and/or 2,6-TDA. Furthermore, the formation of complexes of themetal salts used according to the present invention with primary amines,for example primary aromatic amines, can hinder migration or extractionof these amines from the polyisocyanate polyaddition product. Suchcomplexation prevents migration or extraction of the amine catalysts,too, from the product, which ie reflected in improved fogging behaviorof the foams. In addition, the metal salts can act as oxidationcatalysts and accelerate oxidative degradation of any aromatic aminesformed.

[0045] As metal salts, it is possible to use generally known salts ofmetals, for example salts of inorganic and/or organic acids, e.g.mineral acids, of the transition groups indicated, for example salts ofthe following metals: Cu, Ni, Co, Fe, Zn, Ag, Pd and Rh, preferably Cu,Ni and/or Fe salts, where the metals can be in any stable oxidationstate.

[0046] As anion in the metal salts, it is possible for generallycustomary anions to be present, for example, chloride, sulfate, nitrateand/or carboxylates having from 1 to 20 carbon atoms. Furthermore, it ispossible to use salts of complexed cations of the same metals with knownligands, for example monoalkylamines, alkylenediamines, phenanthroline,acetylacetone, aromatic phosphines such as triphenylphosphine, aliphaticphosphines such as tributylphosphine, salicylaldehyde and/or1,4-diazabutadiene derivatives; it is preferred that no tertiary aminesare used as ligands. Examples of metal salts or salts of their complexcations are the following compounds: Cu(II) sulfate, Cu(II) chloride,Ni(II) sulfate, Co(II) chloride, Cu(II) naphthenate, Fe(II) chloride,Cu(I) chloride, Fe(III) chloride, Cu(II) acetate-ethylenediaminecomplex, Fe(II) phenanthroline complex (generally known as a redoxindicator under the name ferroin), Cu(I)-nitratobistriphenylphosphinecomplex, [glyoxal bis(cyclohexylimine)]chlorocopper(I) complex.

[0047] The central atom and ligand of the metal-ligand complex arepreferably chosen so that the central atom of the complex can formcomplexes with primary aromatic amines or tertiary aliphatic amines orcatalyze their oxidation. The complex between MDA and/or TDA or theamine catalysts and the metal cation of the complex used is preferablymore stable, i.e. the dissociation constant is greater, than the complexcation used. Preference is given to using Cu(II) sulfate, Ni(II)sulfate, Cu(II) acetate, Fe(II) phenanthroline complex,Cu(II)-acetate-ethylenediamine complex, Cu(II) naphthenate and/orCu(I)-nitratobistriphenylphosphine complex as metal salt.

[0048] To produce the polyisocyanate polyaddition products, the metalsalts are preferably used in an amount of from 0.05 to 5% by weight,based on the weight of the sum of the metal salts and the compoundswhich are reactive toward isocyanates.

[0049] The metal salts can be used in the A and/or B components or inthe constituents of these components, preferably in the isocyanatecomponent.

[0050] Furthermore, it can be useful to use (iii) organic and/orinorganic acid anhydrides, particularly preferably at least onecarboxylic anhydride, for producing the polyisocyanate polyadditionproducts. The acid anhydride(s) is/are preferably used in an amount offrom 0.01 to 20% by weight, based on the weight of the isocyanates andthe acid anhydrides.

[0051] When acid anhydrides are employed, the anhydrides in thepolyisocyanate polyaddition products are hydrolyzed to the acids,particularly under hot and humid conditions. These acids resulting fromthe hydrolysis block the amine catalysts which may be present in theproducts, for example by protonation or reaction, and thus preventacceleration of the redissociation of the urethane bonds. In addition,the acid anhydrides used according to the present invention bind anyfree amino groups formed by undesired cleavage of urethane bonds.

[0052] The acid anhydrides are thus used in polyisocyanate polyadditionproducts to stabilize the polyisocyanate polyaddition products, inparticular polyurethanes, against cleavage of the urethane and ureabonds, for example by blocking amine catalysts by protonating thecatalysts or by reaction with the catalysts. In addition, the acidanhydrides can be employed in polyisocyanate polyaddition products toreact with amino groups in the polyisocyanate polyaddition products, forexample to form amides.

[0053] In this way, the diffusion of amines out of the polyisocyanatepolyaddition products and the redissociation of the urethane bond, forexample by amine catalysts present in the polyisocyanate polyadditionproducts, can be reduced.

[0054] It was surprisingly found that acid anhydrides used in theproduction of polyisocyanate polyaddition products survive theproduction process almost unscathed and do not participate significantlyin the reaction. This is particularly true when the acid anhydrides areused in admixture with isocyanates, since this component is usually freeof water and hydrolysis of the anhydrides can thus be avoided. Use ofthe acid anhydrides in admixture with compounds which are reactivetoward isocyanates can be particularly advantageously carried out byadding the acid anhydrides to this mixture only just before productionof the polyisocyanate polyaddition products, since the compounds whichare reactive toward isocyanates usually contain small amounts of water.The acid anhydrides used according to the present invention can also bestable in the isocyanate-reactive compounds over a prolonged period oftime.

[0055] Surprisingly, it has been found that the acid anhydrides arestable in admixture with isocyanates at room temperature, i.e. 25° C.,and the isocyanate groups do not react or do not react significantlywith the anhydride groups.

[0056] As anhydrides, it is possible to use organic or inorganic acidanhydrides, for example also polyanhydrides, preferably carboxylicanhydrides, for example anhydrides of aliphatic, cycloaliphatic,araliphatic and/or aromatic carboxylic acids having usually from 1 to10, preferably 1 or 2, carboxyl groups, with mixed anhydrides preparedfrom at least two different carboxylic acids also being able to be used.Polyanhydrides obtainable from dicarboxylic and/or polycarboxylic acidsor copolymers of anhydrides and various alkenes can also be used asanhydrides. The carboxyl groups of the compounds are preferablyconverted to a large extent, particularly preferably completely, intothe corresponding anhydrides. The compounds (ii) usually have amolecular weight of from 60 to 1000000 g/mol. Examples which may bementioned are: acetic anhydride, propionic anhydride, butyric anhydride,pentanoic anhydride, hexanoic anhydride, heptanoic anhydride, octanoicanhydride, dimethylolpropionic anhydride, adipic anhydride, fumaricanhydride, mesaconic anhydride, methylenemalonic anhydride, trimelliticanhydride, ethylene glycol 4,4′-bis(anhydrotrimellitate),2-acetyl-1,3-glyceryl 4,4′-bisanhydrotrimellitate, decanedioicanhydride, dodecanedioic anhydride, azelaic anhydride, pimelicanhydride, brassylic anhydride, citraconic anhydride, itaconicanhydride, naphthalene-1,8-dicarboxylic anhydride,naphthalene-1,2-dicarboxylic anhydride, chlorendic anhydride,1,2,3,6-tetrahydrophthalic anhydride, mellophanic anhydride,benzene-1,2,3,4-tetracarboxylic anhydride, benzene-1,2,3-tricarboxylicanhydride, benzoic anhydride, biphenyl-3,3′-4,4′-tetracarboxylicanhydride, biphenyl-2,2′-3,3′-tetracarboxylic anhydride,naphthalene-2,3,6,7-tetracarboxylic anhydride,naphthalene-1,2,4,5-tetracarboxylic anhydride,naphthalene-1,4,5,8-tetracarboxylic anhydride,decahydronaphthalene-1,4,5,8-tetracarboxylic anhydride,4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylicanhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic anhydride,2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic anhydride,2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic anhydride,phenanthrene-1,3,9,10-tetracarboxylic anhydride,perylene-3,4,9,10-tetracarboxylic anhydride,bis(2,3-dicarboxyphenyl)methane anhydride,bis(3,4-dicarboxyphenyl)methane anhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane anhydride, 1,1-bis(3,4-dicarboxyphenyl) ethane anhydride,2,2-bis(2,3-dicarboxyphenyl)propane anhydride, 2,2-bis(3,4-dicarboxyphenyl)propane anhydride, bis(3,4-dicarboxyphenyl) sulfoneanhydride, bis(3,4-dicarboxyphenyl) ether anhydride,ethylenetetracarboxylic anhydride, butane-1,2,3,4-tetracarboxylicanhydride, cyclopentane-1,2,3,4-tetracarboxylic anhydride,pyrrolidine-2,3,4,5-tetracarboxylic anhydride,pyrazine-2,3,5,6-tetracarboxylic anhydride, mellitic anhydride,thiophene-2,3,4,5-tetracarboxylic anhydride,benzophenone-3,3′,4,4′-tetracarboxylic anhydride, maleic anhydride,glutaric anhydride, pyromellitic anhydride, phthalic anhydride,isophthalic and/or terephthalic anhydride, benzoic anhydride,phenylacetic anhydride, cyclohexylalkane anhydrides, malonic anhydride,succinic anhydride, polymaleic anhydride, anhydrides based on adducts ofmaleic acid and styrene, dodecenylsuccinic anhydride, anhydrides ofmaleic acid and any alkylenes, for example n-octylenesuccinic anhydride,n-dodecylenesuccinic anhydride and/or copolymers of anhydrides and anyfurther monomers such as isobutene and maleic anhydride,poly(ethylene-co-butyl acrylate-co-maleic dianhydride) and/orpoly(styrene-co-maleic anhydride), where the diacids or polyacids arepartially or preferably completely in the form of anhydrides. Theanhydrides of the diacids or polyacids can, insofar as it is stericallypossible, be either intermolecular or intramolecular.

[0057] Preference is given to using anhydrides based on the followingcompounds: pyromellitic acid, succinic acid, maleic acid, polymaleicanhydride, glutaric acid, which may also contain a variety of sidegroups, and/or copolymers of these anhydrides with all conceivablemonomers which are polymerizable with anhydrides or acids.

[0058] Very particular preference is generally given to anhydrides whichdissolve readily in the isocyanates and/or the compounds which arereactive toward isocyanates, preferably the isocyanates.

[0059] Furthermore, it is possible to use (iv) cyclic sulfonic esters,also known as sultones, and/or sulfones, i.e. compounds containingsulfonyl groups, preferably unsaturated sulfones. The cyclic sulfonicesters and sulfones are hereinafter also referred to collectively as“sulfur compounds”. It has surprisingly been found that the addition ofthe sulfur compounds leads to significantly reduced primary aminecontents. The reaction of primary amines can occur under relatively mildconditions. Apart from the reaction of primary amine already formed togive less problematical compounds, the addition of sulfur compounds, inparticular sultones, prevents the formation of the primary amines. Themechanism leading to this reduced amine formation is based on thedeactivation of the tertiary amine catalysts present, which, after thepolyurethane product has been produced, contribute to catalysis of thehydrolytic cleavage of urethane and urea bonds and thus to the formationof primary amines.

[0060] The added sultones, in particular, are hydrolyzed during thefoaming reaction as a result of the heat generated to form thecorresponding sulfonic acids. These sulfonic acids are in turn capableof reacting with tertiary amines by protonating the catalytically activenitrogen atom. This counters not only the formation of primary aminesbut also the associated deterioration in the mechanical propertiesduring aging of the polyurethane product. As a particular advantage ofthe additives used according to the present invention, it hassurprisingly been found that there is even an improvement in themechanical properties before aging. A further positive effect associatedwith this hydrolysis of the sultones is that a major part of the waterwhich penetrates is consumed in this reaction and is no longer availablefor the cleavage of urethane and urea bonds. In order to preventpremature hydrolysis of the sultones prior to the foaming reaction, theyare preferably dissolved in the isocyanate component.

[0061] In unsaturated sulfones, the sulfonyl group causes, as a resultof the partial positive charge on the sulfur atom, such a strongpolarization of the C═C double bond that this is capable of addingprimary amines under very mild conditions. The primary amine content ofpolyisocyanate polyaddition products can be significantly reduced by theaddition of unsaturated sulfones as a result of reaction to formunproblematical compounds. In addition, sulfones also lead to animprovement in the mechanical properties of the polyisocyanatepolyaddition products.

[0062] The addition of sultones and sulfones can reduce the diffusion ormigration of primary amines out of the polyurethane products. Inhydrolyzed form, sultones improve the fogging behavior by preventingdiffusion of tertiary amine catalysts as a result of the reaction ofthese with the hydrolyzed sultones.

[0063] In the case of brominated sultones (e.g.tetrabromo-2-sulfobenzoic anhydride) and sulfones, an increase in theflame resistance of the foams produced therewith has also been found.

[0064] Accordingly, the sulfur compounds counter both a deterioration inthe mechanical properties, particularly on exposure to hot and humidconditions, and also the formation of primary amines, in particularprimary aromatic amines, for example 2,2′-, 2,4′-and/or 4,4′-MDA and/or2,4- and/or 2,6-TDA.

[0065] The additives used according to the present invention have beenfound to be particularly effective in PUR formulations which containtertiary amines having reactive functional groups as catalysts.

[0066] As sulfur compounds, it is possible to use generally knowncompounds, preferably sultones and/or unsaturated sulfones.

[0067] Examples are: cyclic esters of aliphatic and aromatic sulfonicacids, known as sultones, e.g. 1,3-propanesultone, 1,4-butanesultone,2,4-butanesultone, 2,3-benzopropanesultone, tolylsultone, 2-sulfobenzoiccycloanhydride, tetrabromo-2-sulfobenzoic cycloanhydride,tetraiodo-2-sulfobenzoic cycloanhydride, 1-naphthol-8-sulfonic sultone,carbyl sulfate and/or triphenylmethane dyes containing sultone groups,e.g. phenol red, pyrogallol red, pyrocatechol violet, thymol blue,bromothymol blue, p-xylenol blue, bromoxylenol blue, bromocresol green,bromophenol blue, tetrabromophenol blue, chlorophenol red, cresol red,xylenol orange, bromophenol red, nitrophenolsulfonephthalein,sulfonefluorescein and/or bromopyrogallol red, preferably1,3-propanesultone, 1,4-butanesultone, 2,4-butanesultone, 2-sulfobenzoiccycloanhydride, tetrabromo-2-sulfobenzoic cycloanhydride and1-naphthol-8-sulfonic sultone.

[0068] Unsaturated sulfones which can be used are, for example,butadiene sulfone, divinyl sulfone, benzyl allyl sulfone, allyl sulfone,thionaphthene 1,1-dioxide and/or p-tolyl vinyl sulfone, preferablybutadiene sulfone.

[0069] To produce the polyisocyanate polyaddition products, the sulfurcompounds are preferably used in an amount of from 0.01 to 20% byweight, based on the weight of the polyisocyanate polyaddition product.

[0070] Furthermore, it is possible to use (v) lactones, lactams and/orcyclic esters, hereinafter also referred to as “inhibitors”.

[0071] The addition of the inhibitors in PUR foam formulationssurprisingly leads to significantly reduced contents of primary amines.As inhibitors to be used according to the present invention for reducingthe primary amine content in polyurethane products, we have accordinglyfound lactones or cyclic esters and lactams. As experiments have shown,there are various mechanisms which contribute to this reduction. Thehydrolysis of lactones in the presence of moisture to formhydroxycarboxylic acids is known from the literature. The carboxylicacid formed by hydrolysis of the inhibitor is capable of protonating thetertiary N atom in the amine catalyst. As a result of the catalyticallyactive N atom being blocked with formation of a quaternary N atom, theamine catalyst loses its catalytic activity in respect of the hydrolyticredissociation of urethane and urea bonds. This counters a deteriorationin the mechanical properties of the polyisocyanate polyadditionproducts, in particular the flexible foams, especially when exposed tohot and humid conditions, and also the formation of primary amines, inparticular primary aromatic amines, for example 2,2′-, 2,4′- and/or4,4′-MDA and/or 2,4- and/or 2,6-TDA. The addition of the inhibitorsreduces the hydrolysis of urethane and urea bonds in two ways: asmentioned by deactivating the amine catalysts present and also as aresult of a major part of the water which penetrates being consumed inthe hydrolysis of the lactones and lactams added and no longer beingavailable for the cleavage of urethane and urea bonds. Moreover, theinhibitors are also capable of reacting with primary amine which hasalready been formed to give hydroxycarboxamides or aminocarboxamides.

[0072] The addition of the inhibitors can reduce the diffusion ormigration of primary amines out of the polyurethane products byconverting the primary amines into hydroxycarboxamides oraminocarboxamides. The relatively high molecular weight of the reactionproducts, in particular when using lactones of higher carboxylic acids,e.g. of hydroxydecanoic acid or of hydroxydodecanoic acid, reducesdiffusion or migration out of the polyurethane matrix so that thefogging behavior is improved.

[0073] After they have been hydrolyzed, lactams and lactones also effectan improvement in the fogging behavior of polyurethane products bypreventing diffusion of the tertiary amine catalysts used by protonatingthem. Furthermore, in some applications it is desirable to increase thecrosslinking density of polyurethane foams, in particular flexiblepolyurethane foams, by modification of the formulation (increasing theproportion of crosslinker, use of multiring MDI, increasing the index)without, however, increasing the hardness too much at the same time. Theaddition of lactones and lactams, which also function as plasticizers,makes it possible to compensate for this undesired increase in hardness.

[0074] Examples of inhibitors which can be used according to the presentinvention are the following compounds:

[0075] Lactones, for example those having a molecular weight of from 70to 300 g/mol, e.g. β-propiolactone, γ-butyrolactone, γ-valerolactone,ε-caprolactone, γ-decanolactone, δ-decanolactone, δ-dodecanolactone,γγ-dimethylbutyrolactone and/or α-ethyl-γ-methylbutyrolactone.

[0076] Lactams, for example those having a molecular weight of from 70to 300 g/mol, e.g. β-propiolactam, 2-pyrrolidone, N-methylpyrrolidoneand 2-piperidone.

[0077] Cyclic esters, for example those having a molecular weight offrom 150 to 500 g/mol, preferably condensation products of aliphatic,cycloaliphatic, araliphatic and/or aromatic dicarboxylic acids havingfrom 4 to 15 carbon atoms and aliphatic, cycloaliphatic, araliphaticand/or aromatic dialcohols having from 2 to 15 carbon atoms,particularly preferably condensation products based on diethylene glycol(DEG) and adipic acid (ADA). These cyclic esters, for example the cyclicDEG-ADA ester and the cyclic ADA-DEG-ADA-DEG ester, are found, alongwith DEG and low molecular weight linear esters, in an amount of about40-50% by mass in a distillation residue obtained in the synthesis ofpolyester polyols based on ADA-DEG-trimethylolpropane and areaccordingly particularly economically advantageous to use.

[0078] To produce the polyisocyanate polyaddition products, theinhibitors are preferably used in an amount of from 0.01 to 20.0% byweight, based on the weight of the compounds which are reactive towardisocyanates.

[0079] Furthermore, generally known α,β-unsaturated carboxylic acids,α,β-unsaturated carboxylic acid derivatives, α,β-unsaturated ketonesand/or α,β-unsaturated aldehydes as (vi) can advantageously be used.

[0080] As a result of the use of (vi), any free amino groups formed byundesired cleavage of urethane and/or urea groups are bound by reactionwith the compounds (vi) used according to the present invention.

[0081] Both primary and secondary amines are capable of addition to C═Cdouble bonds, particularly if these are adjacent to a carbonyl group.This Michael addition of the amine occurs onto the unsaturated system inwhich the π-electrons are delocalized over the carbonyl group. As hasbeen found in experiments, temperatures of from 70 to 120° C. as can beencountered under hot and humid conditions, for example in hot steamsterilization or cleaning with hot steam, are very surprisinglysufficient to react at least some of the primary amine formed in the PURfoam by hydrolytic cleavage of urethane and urea bonds with thecompounds (vi). The amino groups are bound to the α,β-unsaturatedcarbonyl compounds used according to the present invention by additiononto the C═C double bonds with formation of a covalent bond. Thediffusion or migration of primary amines out of the polyurethane foamscan thus be reduced according to the present invention. This isparticularly true when the compounds (vi) are built into thepolyurethane network being formed as a result of the presence of groupssuch as OH or NH₂ capable of being incorporated into the polyurethanestructure. In this way, not only are the compounds (vi) fixed and theirdiffusion from the polyurethane foams is thereby prevented, but theprimary amine bound to the compound (vi) is likewise immobilized.

[0082] Preference is given to compounds (vi) which have the followingstructural feature:

[0083] where the radicals R¹ to R⁴ have the following meanings:

[0084] R¹: H, C₁-C₁₂-alkyl, C₆-C₂₀-aryl,

[0085] R²: H, C₁-C₁₂-alkyl, C₆-C₂₀-aryl,

[0086] R³: H, C₁-C₁₂-alkyl, C₆-C₂₀-aryl,

[0087] R⁴: H, C₁-C₁₂-alkyl, C₆-C₂₀-aryl, —O—C₁-C₁₂-alkyl,—O—C₁-C₁₂-alkyl-OH, —C₁-C₁₂-alkyl-OH, —O—C₁-C₁₂-alkyl,—C₁-C₁₂-alkyl-NH₂, —O—C₁-C₁₂-alkyl-NH₂, —O-benzyl, —O-aryl,—O—C₁-C₁₂-alkyl-COOH, —O—C₁-C₁₂-alkyl-CH(OH)—CH₂—O— (CO)—CHCH₂,—O—C₁-C₁₂-alkyl-O—(CO)—CHCH₂.

[0088] As (vi), particular preference is given to the followingcompounds: acrylic acid, crotonic acid, isocrotonic acid, sorbic acid,fumaric acid, cinnamic acid, hydroxyethyl acrylate,3-(acryloyloxy)-2-hydroxypropyl methacrylate, benzyl cinnamate,trans-3-nonen-2-one, benzalacetone, dibenzalacetone, benzalacetophenone,1-methylbenzalacetophenone, crotonaldehyde, cinnamaldehyde, methyl vinylketone and/or α,β-unsaturated polyester diols prepared bypolycondensation of maleic acid, fumaric acid and/or acrylic acid witholigomeric diols such as butanediol, diethylene glycol, propyleneglycol, 1,3-propanediol and/or triols such as glycerol and having amolecular weight factor per double bond of from 150 to 3000, afunctionality of from 2 to 6, a hydroxyl number of from 20 to 800 mgKOH/g and an acid number of from 0 to 15.

[0089] In particular, the following compounds are used as (vi):hydroxyethyl acrylate, 3-(acryloyloxy)-2-hydroxypropylmethacrylate,trans-3-nonen-2-one, benzyl cinnamate, crotonic acid and/orα,β-unsaturated polyester diols (A) prepared by polycondensation ofmaleic acid, fumaric acid or acrylic acid with oligomeric diols such asbutanediol, diethylene glycol, propylene glycol, 1,3-propanediol and/ortriols such as glycerol and having a molecular weight factor per doublebond of from 150 to 3000, a functionality of from 2 to 6, a hydroxylnumber of from 20 to 800 mg KOH/g and an acid number of from 0 to 15.

[0090] α,β-unsaturated carbonyl compounds having additional functionalgroups such as OH and NH₂ which are built into the PUR network lead to aparticularly significant reduction in the MDA and TDA contents. Exampleswhich may be mentioned are hydroxyethyl acrylate and3-(acryloyloxy)-2-hydroxypropyl methacrylate. Polyols containingintegrated C═C double bonds conjugated with the carbonyl group act in asimilar way.

[0091] In general, particular preference is given to compounds (vi)which dissolve readily in the isocyanates or the compounds which arereactive toward isocyanates. The compounds (vi) are preferably used inadmixture with the isocyanates.

[0092] In the process of the present invention for producingpolyurethane foams, (vi) is preferably used in an amount of from 0.1 to20% by weight, particularly preferably from 0.5 to 10% by weight, basedon the weight of the polyisocyanate polyaddition products.

[0093] The polyurethane foams obtainable according to the presentinvention have the particular advantage that any primary amines, inparticular primary aromatic amines, formed by hydrolysis are convertedinto an unproblematical form by means of the compounds (vi). Thepolyurethane foams, in particular mattresses, furniture upholstery orfoam backing for carpets, thus particularly preferably contain productsof the reaction of primary and/or secondary amines, preferably aromaticamines, with the abovementioned compounds (vi), i.e. the α,β-unsaturatedcarboxylic acids, α,β-unsaturated carboxylic acid derivatives,α,β-unsaturated ketones and/or α,β-unsaturated aldehydes.

[0094] The compounds described above, i.e. the hydrophobic compounds andalso (i) organic, cyclic compounds having a molecular weight of from 200to 3000 g/mol, (ii) salts of metals of transition groups I, II and/orVIII, (iii) organic and/or inorganic acid anhydrides, (iv) cyclicsulfonic esters and/or sulfones, (v) lactones, lactams and/or cyclicesters and/or (vi) α,β-unsaturated carboxylic acids, α,β-unsaturatedcarboxylic acid derivatives, α,β-unsaturated ketones and/orα,β-unsaturated aldehydes, can be used for producing polyisocyanatepolyaddition products by generally known methods, for example byreacting isocyanates with compounds which are reactive towardisocyanates in the presence or absence of catalysts, blowing agents,additives and/or auxiliaries. For example, compact or cellular, forexample microcellular, flexible, semirigid or rigid polyurethane foams,thermoplastic polyurethanes or polyurethane elastomers can be producedas polyisocyanate polyaddition products by customary methods using theinhibitors employed according to the present invention. The compoundsdescribed are preferably used in processes for producing polyurethaneelastomers or foamed polyisocyanate polyaddition products, in particularflexible polyurethane foams having a density of from 15 to 300 kg/m³,preferably from 2 to 70 kg/m³, preferably mattresses and/or furnitureupholstery or carpet backing, in particular hospital mattresses, byreacting isocyanates with compounds which are reactive towardisocyanates in the presence of catalysts, blowing agents and, ifdesired, additives and/or auxiliaries. These products, i.e. inparticular the furniture upholstery and/or carpet backing or themattresses, are increasingly treated with hot steam for the purpose ofcleaning or disinfection, so that it is precisely these products inwhich the advantages obtained according to the present invention areparticularly pronounced.

[0095] The generally customary starting materials for producing thepolyisocyanate polyaddition products are described below by way ofexample.

[0096] As isocyanates, it is possible to use the aliphatic,cycloaliphatic, araliphatic and preferably aromatic organic isocyanatesknown per se, preferably polyfunctional isocyanates, particularlypreferably diisocyanates.

[0097] Specific examples are: alkylene diisocyanates having from 4 to 12carbon atoms in the alkylene radical, e.g. dodecane 1,12-diisocyanate,2-ethyltetramethylene 1,4-diisocyanate, 2-methylpentamethylene1,5-diisocyanate, tetramethylene 1,4-diisocyanate and preferablyhexamethylene 1,6-diisocyanate; cycloaliphatic diisocyanates such ascyclohexane 1,3- and 1,4-diisocyanate and also any mixtures of theseisomers, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane(isophorone diisocyanate), hexahydrotolylene 2,4- and 2,6-diisocyanateand also the corresponding isomer mixtures, dicyclohexylmethane 4,4′-,2,2′- and 2,4′-diisocyanate and also the corresponding isomer mixtures,aromatic diisocyanates and polyisocyanates, e.g. tolylene 2,4- and2,6-diisocyanate (TDI) and the corresponding isomer mixtures,diphenylmethane 4,4′-, 2,4′- and 2,2′-diisocyanate (MDI) and thecorresponding isomer mixtures, naphthalene 1,5-diisocyanate (NDI),mixtures of diphenylmethane 4,4′- and 2,4′-diisocyanates, mixtures ofNDI and diphenylmethane 4,4′- and/or 2,4′-diisocyanates,3,3′-dimethyl-4,4′-diisocyanatobiphenyl (TODI), mixtures of TODI anddiphenylmethane 4,4′- and/or 2,4′-diisocyanates, polyphenylpolymethylenepolyisocyanates, mixtures of diphenylmethane 4,4′-, 2,4′- and2,2′-diisocyanates and polyphenylpolymethylene polyisocyanates (crudeMDI) and mixtures of crude MDI and tolylene diisocyanates. The organicdiisocyanates and polyisocyanates can be used individually or in theform of their mixtures.

[0098] Use is frequently also made of modified polyfunctionalisocyanates, i.e. products which are obtained by chemical reaction oforganic diisocyanates and/or polyisocyanates. Examples which may bementioned are diisocyanates and/or polyisocyanates containing ester,urea, biuret, allophanate, carbodiimide, isocyanurate, uretdione and/orurethane groups specific examples of suitable modified isocyanates are:organic, preferably aromatic polyisocyanates containing urethane groupsand having NCO contents of from 33.6 to 15% by weight, preferably from31 to 21% by weight, based on the total weight, modified diphenylmethane4,4′-diisocyanate, modified diphenylmethane 4,4′- and 2,4′-diisocyanatemixtures, modified NDI, modified TODI, modified crude MDI and/ortolylene 2,4- or 2,6-diisocyanate, with examples of dialkylene glycolsor polyoxyalkylene glycols which can be used individually or as mixturesbeing: diethylene glycol, dipropylene glycol, polyoxyethylene,polyoxypropylene and polyoxypropylene-polyoxyethylene glycols, triolsand/or tetrols. Also suitable are prepolymers containing NCO groups,having NCO contents of from 25 to 3.5% by weight, preferably from 21 to14% by weight, based on the total weight, and prepared from, forexample, polyester polyols and/or preferably polyether polyols anddiphenylmethane 4,4′-diisocyanate, mixtures of diphenylmethane 2,4′- and4,4′-diisocyanate, NDI, TODI, mixtures of NDI and isomers of MDI,tolylene 2,4- and/or 2,6-diisocyanates or crude MDI. Further modifiedisocyanates which have been found to be useful are liquidpolyisocyanates containing carbodiimide groups and/or isocyanurate ringsand having NCO contents of from 33.6 to 15% by weight, preferably from31 to 21% by weight, based on the total weight, e.g. ones based ondiphenylmethane 4,4′-, 2,4′- and/or 2,2′-diisocyanate, NDI, TODI and/ortolylene 2,4′- and/or 2,6-diisocyanate.

[0099] The modified polyisocyanates may, if desired, be mixed with oneanother or with unmodified organic polyisocyanates such asdiphenylmethane 2,4′- and/or 4,4′-diisocyanate, NDI, TODI, crude MDI andtolylene 2,4- and/or 2,6-diisocyanate.

[0100] Isocyanates which are preferably used in the mixtures employedaccording to the present invention or the process of the presentinvention are diphenylmethane 4,4′-, 2,4′- and/or 2,2′-diisocyanate,tolylene 2,4- and/or 2,6-diisocyanate, NDI, hexamethylene diisocyanateand/or isophorone diisocyanate, with these isocyanates being able to beused in any mixtures or in modified form as described above.

[0101] As isocyanate-reactive compounds, if desired in addition to thehydrophobic compounds used according to the present invention, insofaras the latter are reactive toward isocyanates, usually having at leasttwo reactive hydrogen atoms, usually hydroxyl and/or amino groups, usecan advantageously be made of those having a functionality of from 2 to8, preferably from 2 to 6, and a molecular weight of usually from 60 to10000. Compounds which have been found to be useful are, for example,polyetherpolyamines and/or preferably polyols selected from the groupconsisting of polyether polyols, polyester polyols, polythioetherpolyols, polyesteramides, hydroxyl-containing polyacetals andhydroxyl-containing aliphatic polycarbonates or mixtures of at least twoof the polyols mentioned. Preference is given to using polyester polyolsand/or polyether polyols which can be prepared by known methods.

[0102] The polyester polyols preferably have a functionality of from 2to 4, in particular from 2 to 3, and a molecular weight of usually from500 to 3000 g/mol, preferably from 1200 to 3000 g/mol and in particularfrom 1800 to 2500 g/mol.

[0103] The polyether polyols have a functionality of preferably from 2to 6 and usually have molecular weights of from 500 to 8000.

[0104] Suitable polyether polyols also include, for example,polymer-modified polyether polyols, preferably graft polyether polyols,in particular those based on styrene and/or acrylonitrile which can beprepared by in situ polymerization of acrylonitrile, styrene orpreferably mixtures of styrene and acrylonitrile.

[0105] Like the polyester polyols, the polyether polyols can be usedindividually or in the form of mixtures. They can also be mixed with thegraft polyether polyols or polyester polyols or with hydroxyl-containingpolyesteramides, polyacetals and/or polycarbonates.

[0106] Polyol components used for rigid polyurethane foams which maycontain isocyanurate structures are high-functionality polyols, inparticular polyether polyols based on high-functionality alcohols, sugaralcohols and/or saccharides as initiator molecules while polyols usedfor flexible foams are 2- and/or 3-functional polyether polyols and/orpolyester polyols based on glycerol and/or trimethylolpropane and/orglycols as initiator molecules or alcohols to be esterified. Thepolyether polyols are prepared using a known technology. Suitablealkylene oxides for preparing the polyols are, for example,tetrahydrofuran, 1,3-propylene oxide, 1,2- or 2,3-butylene oxide,styrene oxide and preferably ethylene oxide and 1,2-propylene oxide. Thealkylene oxides can be used individually, alternately in succession oras mixtures. Preference is given to using alkylene oxides which lead toprimary hydroxyl groups in the polyol. Particular preference is given tousing polyols which have been alkoxylated using ethylene oxide at theconclusion of the alkoxylation and therefore have primary hydroxylgroups. For producing thermoplastic polyurethanes, preference is givento using polyols having a functionality of from 2 to 2.2 and nocrosslinker.

[0107] As compounds which are reactive toward isocyanates, it is alsopossible to use chain extenders and/or crosslinkers. The addition ofchain extenders, crosslinkers or, if desired, mixtures thereof can proveto be advantageous for, for example, modifying the mechanicalproperties, e.g. the hardness, of the polyisocyanate polyadditionproducts produced using these substances. Chain extenders and/orcrosslinkers which can be used are water, diols and/or triols havingmolecular weights of from 60 to <500, preferably from 60 to 300.Examples of suitable chain extenders/crosslinkers are aliphatic,cycloaliphatic and/or araliphatic diols having from 2 to 14, preferablyfrom 4 to 10, carbon atoms, for example ethylene glycol,1,3-propanediol, 1,10-decanediol, o-, m-, p-dihydroxycyclohexane,diethylene glycol, dipropylene glycol and preferably 1,4-butanediol,1,6-hexanediol and bis(2-hydroxyethyl)hydroquinone, triols such as1,2,4- or 1,3,5-trihydroxycyclohexane, glycerol and trimethylolpropaneand low molecular weight hydroxyl-containing polyalkylene oxides basedon ethylene oxide and/or 1,2-propylene oxide and diols and/or triols asinitiator molecules.

[0108] If chain extenders, crosslinkers or mixtures thereof are employedfor producing the polyisocyanate polyaddition products, they areadvantageously used in an amount of from 0 to 20% by weight, preferablyfrom 2 to 8% by weight, based on the weight of the compounds which arereactive toward isocyanates; thermoplastic polyurethanes are preferablyproduced without a crosslinker.

[0109] Suitable catalysts are generally customary compounds, for exampleorganic amines such as triethylamine, triethylenediamine, tributylamine,dimethylbenzylamine, N,N,N′,N′-tetramethylethylenediamine,N,N,N′,N′-tetramethylbutanediamine,N,N,N′,N′-tetramethylhexane-1,6-diamine, dimethylcyclohexylamine,pentamethyldipropylenetriamine, pentamethyldiethylenetriamine,3-methyl-6-dimethylamino-3-azapentol, dimethylaminopropylamine,1,3-bis(dimethylamino)butane, bis(2-dimethylaminoethyl) ether,N-ethylmorpholine, N-methylmorpholine, N-cyclohexylmorpholine,2-dimethylaminoethoxyethanol, dimethylethanolamine,tetramethylhexamethylenediamine, dimethylamino-N-methylethanolamine,N-methylimidazole, N-(3-aminopropyl)imidazole,N-(3-aminopropyl)-2-methylimidazole, 1-(2-hydroxyethyl)imidazole,N-formyl-N,N′-dimethylbutylenediamine, N-dimethylaminoethylmorpholine,3,3′-bis(dimethylamino)-di-n-propylamine and/or2,2′-bis(2-piperazinoisopropyl) ether, dimethylpiperazine, N,N′-bis(3-aminopropyl) ethylenediamine and/ortris(N,N-dimethylaminopropyl)-s-hexahydrotriazine, or mixturescomprising at least two of the amines mentioned. Also possible arerelatively high molecular weight tertiary amines as are described, forexample, in DE-A 28 12 256. Further catalysts which can be used for thispurpose are customary organic metal compounds, preferably organic tincompounds such as tin(II) salts of organic carboxylic acids, e.g.tin(II) acetate, tin(II) octoate, tin(II) ethylhexanoate and tin(II)laurate and the dialkyltin(IV) salts of organic carboxylic acids, e.g.dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate anddioctyltin diacetate. Tertiary aliphatic and/or cycloaliphatic aminesare preferably present in the mixtures, particularly preferablytriethylenediamine.

[0110] As blowing agents, it is possible to use, if desired, preferablyfor producing foamed polyurethanes, generally known blowing agents suchas materials which have a boiling point at atmospheric pressure in therange from −40° C. to 120° C., gases and/or solid blowing agents and/orwater in customary amounts, for example carbon dioxide, alkanes and/orcycloalkanes, e.g. isobutane, propane, n- or iso-butane, n-pentane andcyclopentane, ethers such as diethyl ether, methyl isobutyl ether anddimethyl ether, nitrogen, oxygen, helium, argon, nitrous oxide,halogenated hydrocarbons and/or partially halogenated hydrocarbons, e.g.trifluoromethane, monochlorotrifluoroethane, difluoroethane,pentafluoroethane or tetrafluoroethane, or mixtures comprising at leasttwo of the blowing agents mentioned by way of example.

[0111] Examples of auxiliaries and/or additives are surface-activesubstances, foam stabilizers, cell regulators, fillers, dyes, pigments,flame retardants, hydrolysis inhibitors, fungistatic and bacteriostaticsubstances.

[0112] The organic polyisocyanates and the isocyanate-reactive compoundshaving a molecular weight of from 60 to 10000 g/mol are usually reactedin such amounts that the equivalence ratio of NCO groups of thepolyisocyanates to the sum of the reactive hydrogen atoms of theisocyanate-reactive compounds is 0.5-5:1, preferably 0.9-3:1 and inparticular 0.95-2:1.

[0113] It may be advantageous for the polyurethanes to contain at leastsome bound isocyanurate groups. In these cases, the ratio of NCO groupsof the polyisocyanates to the sum of the reactive hydrogen atoms isadvantageously 1.5-60:1, preferably 1.5-8:1.

[0114] The polyisocyanate polyaddition products can, for example, beproduced by the one-shot method or the known prepolymer method, forexample with the aid of the high-pressure or low-pressure technique inopen or closed molds, reaction extruders or belt units.

[0115] The mixtures used according to the present invention arepreferably employed for producing foamed polyisocyanate polyadditionproducts, for example foamed polyurethanes and/or polyisocyanurates.

[0116] It has been found to be advantageous to produce thepolyisocyanate polyaddition products by the two-component process and tocombine the compounds which are reactive toward isocyanates and, ifdesired, the catalysts, blowing agents and/or auxiliaries and/oradditives as the A component and to use the isocyanates and catalystsand/or blowing agents as the B component. The hydrophobic compounds can,if they have no groups which are reactive toward isocyanates, be used inthe A and/or B component or in the constituents of these components.Hydrophobic compounds which have groups which are reactive towardisocyanates, for example hydroxyl groups, are preferably used in thepolyol component.

[0117] The invention is illustrated by the following examples.

EXAMPLES

[0118] In order to simulate conditions as can occur in theabovementioned specific applications, aging under hot and humidconditions was carried out on specimens of the flexible foams mentionedbelow. For this purpose, test cubes having an edge length of 3 cm wereaged at 90° C. and 90% relative atmospheric humidity for 72 hours in anair conditioned chamber. Under these conditions, hydrolytic cleavage ofurethane and urea bonds and thus the formation of aromatic amines canoccur. The amine formed was subsequently extracted by means of a methoddeveloped by Prof. Skarping, University of Lund. For this purpose, thefoam is squeezed out 10 times with 10 ml of acetic acid (w=1% byweight). The acetic acid was, with the foam specimen compressed,transferred to a 50 ml volumetric flask. The process was repeated threetimes and the volumetric flask was made up to the mark with acetic acid.

[0119] The MDA content of the combined extracts was subsequentlydetermined by means of capillary electrophoresis with UV detection. TheMDA and TDA contents reported in the tables correspond to the absolutecontents of MDA and TDA formed in the PUR foam.

[0120] 1) Flexible polyurethane foam, hereinafter referred to asComparative System 1, produced by mixing 750 g of A component with 354 gof B component (index: 90) and transferring the foaming mixture into analuminum mold (40×40×10 cm) heated to 53° C., with the components havingthe following compositions:

[0121] A Component   97 parts by weight of a polyol having an OHN of 28,a mean functionality of 2.3 and an EO/PO ratio of 14/86,   3 parts byweight of a polyol having an OHN of 42, a mean functionality of 3 and aPO/EO ratio of 30/70,  3.31 parts by weight  of water, 0.8 part byweight of aminopropylimidazole, 0.6 part by weight of Lupragen ® N107,OHN: ′421 (BASF Aktiengesellschaft), 0.5 part by weight of Tegostab ® B8631 (Goldschmidt)

[0122] B Component

[0123] Mixture of 50% of a polymeric MDI and 50% of a 1:1 mixture of2,4′-MDI and 4,4′-MDI.

[0124] This system includes aminopropylimidazole and2-(2-dimethylaminoethoxy)ethanol as catalysts which can be built intothe polyurethane structure. It was selected to demonstrate theparticular effectiveness of the additives in PUR formulations containingcatalysts and catalytically active spacer polyols which can be builtinto the PUR network.

[0125] 2) Flexible polyurethane foam (index: 90), hereinafter referredto as Comparative System 2, which was employed as a model for standardflexible foams, produced by mixing 750 g of A component with 354 g of Bcomponent (index: 90) and transferring the foaming mixture into analuminum mold (40×40×10 cm) heated to 53° C., with the components havingthe following compositions:

[0126] A Component   97 parts by weight of a polyol having an OHN of 28,a mean functionality of 2.3 and an EO/PO ratio of 14/86,   3 parts byweight of a polyol having an OHN of 42, a mean functionality of 3 and aPO/EO ratio of 30/70,  3.31 parts by weight of water, 0.22 part byweight of 1,4-diazabicyclo[2.2.2]octane, 0.14 part by weight ofLupragen ® N 206 (BASF Aktiengesellschaft),  0.5 part by weight ofTegostab ® B 8631 (Goldschmidt)

[0127] B Component

[0128] Mixture of 50% of a polymeric MDI and 50% of a 1:1 mixture of2,4′-MDI and 4,4′-MDI.

[0129] 3) Flexible polyurethane foam (index: 90), hereinafter referredto as Comparative System 3, produced from:

[0130] A Component   100 parts by weight of a polyol having an OHN of35, a mean functionality of 3.0 and an EO/PO ratio of 13.3/86.4,  3.31parts by weight of water, 0.35 part by weight of Lupragen ® N 201(BASF), 0.38 part by weight of tin dioctoate,  1.0 part by weight ofTegostab ® B 8680 (Goldschmidt)

[0131] B Component:

[0132] Mixture of 50% of a polymeric MDI and 50% of a 1:1 mixture of2,4′-MDI and 4,4′-MDI.

[0133] 4) Flexible polyurethane foam (index: 90), hereinafter referredto as Comparative System 4, produced by mixing 750 g of A component with275 g of B component (index: 115) and transferring the foaming mixtureto an open mold having a capacity of 40 l, with the components havingthe following compositions:

[0134] A Component   100 parts by weight of Lupranol ® 2080 (BASFAktiengesellschaft),  4.50 parts by weight of water, 0.30 part by weightof Dabco ® 33LV (Air Products), 0.20 part by weight of tin dioctoate,1.00 part by weight of silicone stabilizer BF 2370

[0135] B Component

[0136] Lupranat® T 80 (BASF Aktiengesellschaft)

[0137] 5) Flexible polyurethane foam (index: 90), hereinafter referredto as Comparative System 5, produced from:

[0138] A Component   100 parts of Lupranol ® 2080 (BASFAktiengesellschaft),  3.80 parts of water 0.15 part of Dabco ® 33LV (AirProducts), 0.26 part of tin dioctoate, 0.05 part of Niax ® A1 (OSI),1.00 part of silicone stabilizer BF 2370

[0139] B Component

[0140] Lupranat® T 80 (BASF Aktiengesellschaft)

[0141] In Table 1, the chemical and physical properties of thehydrophobic compounds used are compared. TABLE 1 Chemical and physicalproperties of the hydrophobic compounds OH number [mg Viscosity Oxiranecontent Hydrophobic compound KOH/g] [mPas] [%] 1 (Kraton liquid 3350000  0.00   polymer L 2203) 2 (Merginat PV 235) 250-300 1200-2000 2.593 (Merginat PV 300) 85 2990  1.77 4 (Sovermol 1137/05) 50-80 10000-140000.00 5 61 955 6 80 565

[0142] Chemical nature of the hydrophobic compounds:

[0143] 1: Hydroxy-functionalized polyethylene-polybutylene, Shell

[0144] 2: Branched oleochemical polyol, HOBUM

[0145] 3: Branched oleochemical polyol, HOBUM

[0146] 4: Slightly branched fat-chemical polyester, Henkel

[0147] 5: Polyester polyol based on ADA/Pripol 1017 (Unichema)/DEG/TMP,where Pripol 1017 (BASF Aktiengesellschaft) is a dimeric fatty acidester and is present in 5 in an amount of about 10%

[0148] 6: Polyether polyol based on castor oil/PO, BASFAktiengesellschaft

[0149] ADA: Adipic acid

[0150] PO: Propylene oxide

[0151] DEG: Diethylene glycol

[0152] TMP: Trimethylolpropane TABLE 2 Summary of Examples 1 to 15Amount of Hydrophobic hydrophobic compound Comparative compound [% byweight in A Example System added component] 1 1 — — 2 1 2  1 3 1 2  2 41 2  5 5 1 2 11 6 1 4 11 7 1 3 11 8 2 — — 9 2 2 11 10 3 — — 11 3 1 10 124 — — 13 4 5 30 14 5 — — 15 5 6 100 

[0153] Comparative Systems 1 to 5 were produced with and withoutaddition of the hydrophobic compounds listed in Table 1.

[0154] In the Examples summarized in Table 2, the proportion in % byweight indicated in the table of the base polyol of the respective Acomponent described under 1) to 5) was in each case replaced by ahydrophobic compound having at least two groups which are reactivetoward isocyanates or a mixture of hydrophobic compounds having at leasttwo groups which are reactive toward isocyanates.

[0155] Table 3 compares the MDA or TDA contents of Examples 1 to 15 withand without addition of hydrophobic compounds which in each case have atleast two groups which are reactive toward isocyanates. TABLE 3Comparison of the MDA contents of flexible PUR foams with and withoutaddition of hydrophobic compounds having at least two groups which arereactive toward isocyanates 4,4′-MDA 2,4′-MDA 4,4′-MDA 2,4′-MDA Creamtime Gel time Rise time [ppm] [ppm] [ppm] [ppm] Example [s] [s] [s]w.o.a. w.o.a. w.a. w.a. 1 13 80 100 <1 <1 397  687  2 20 75 110 <1 <1139  275  3 20 80 115 <1 <1 109  225  4 20 80 115 <1 <1 90 94 5 12 75105 <1 <1 56 141  6 15 90 105 <1 <1 87 200  7 15 85 135 <1 <1 96 207  813 45  80 <1 <1 32 78 9 13 55  95 <1 <1 24 66 10 15 95 130 <1 <1 53 153 11 25 150  180 <1 <1 11 27 12 — — — <1 <1 69 35 13 — — — <1 <1 24 15 14— — — <1 <1 69 35 15 — — — <1 <1 17  9

[0156] Table 4 presents examples in which further compounds from thegroup consisting of (i), (ii), (iii), (iv), (v) and (vi) which arecapable of further reducing the primary amine content were added inaddition to the hydrophobic compounds to the polyurethane foamformulations. Table 5 shows the corresponding results. TABLE 4 Foamsproduced by addition of 2 parts of the hydrophobic compound 2 and afurther compound from the group consisting of (i), (ii), (iii), (iv),(v) and (vi) for reducing the primary amine content Amount of additiveComparative [% by weight dissolved Example System Additive added in Acomponent] 16 1 Lupragen VP 9198 10 17 1 1-naphthol-8-  2 sulfonicsultone

[0157] Lupragen® VP 9198 (BASF Aktiengesellschaft): α,β-unsaturatedpolyester diol having an OH number of 336 mg KOH/g, an acid number of0.7 and a molecular weight factor per double bond of 262, prepared bypolycondensation of maleic anhydride, 1,3-propanediol and diethyleneglycol in a molar ratio of 1:1:1. TABLE 5 Results of Examples 16 and 174,4′-MDA 2,4′-MDA 4,4′-MDA 2,4′-MDA Cream time Gel time Rise time [ppm][ppm] [ppm] [ppm] Example [s] [s] [s] w.o.a. w.o.a. w.a. w.a. 16 21 117150 <1 <1 33 82 17 14  83 — <1 <1 33 89

[0158] The detection limit of the capillary electrophoreticdetermination is 1 ppm.

[0159] As the MDA and TDA contents in Examples 1 to 12 show, theadvantages obtained according to the present invention, i.e. thesignificantly reduced content of primary aromatic amines after agingunder hot and humid conditions due to the addition of hydrophobiccompounds, were able to be demonstrated convincingly. The reducedcontent of aromatic amines is based on their formation being preventedby the addition of the hydrophobic compounds reducing the penetration ofmoisture into the interior of the foam and thus countering hydrolyticcleavage of urethane and urea bonds.

1. A polyisocyanate polyaddition product comprising hydrophobiccompounds plus at least one further compound and/or derivative thereofreactive toward primary amines, said at least one further compound beingselected from the group of cyclic sulfonic esters and sulfones andmixtures thereof, wherein said hydrophobic compounds are selected fromthe group of reaction products of castor oil with alkylene oxides,epoxidized fatty acid esters, low molecular weight hydroxy-functionalpolyolefins and oleochemical polyols based on a C₉-C₂₂-fatty acid andprepared by ring opening of epoxidized triglycerides.
 2. A flexiblepolyurethane foam comprising the polyaddition product of claim
 1. 3-4.(Cancelled)
 5. A mattress or furniture upholstery and/or carpet backingcomprising a flexible polyurethane foam as claimed in claim
 2. 6.(canceled)
 7. A method of reducing the primary amine content ofpolyisocyanate polyaddition products comprising the step of providing insaid polyaddition product a hydrophobic compound and at least onefurther compound and/or derivative thereof, reactive toward primaryamines, said at least one further compound being selected from the groupof cyclic sulfonic esters and sulfones and mixtures thereof, whereinsaid hydrophobic compounds are selected from the group of reactionproducts of castor oil with alkylene oxides, epoxidized fatty acidesters, low molecular weight hydroxy-functional polyolefins andoleochemical polyols based on a C₉-C₂₂-fatty acid and prepared by ringopening of epoxidized triglycerides.
 8. (canceled)
 9. The polyisocyanatepolyaddition product of claim 1 wherein the at least one furthercompound and/or derivative thereof is reactive toward and/or complexeswith tertiary amines.
 10. A polyisocyanate polyaddition productcomprising a hydrophobic flexible polyurethane foam which compriseshydrophobic compounds plus at least one further compound and/orderivative thereof reactive toward primary amines, said at least onefurther compound being selected from the group of cyclic sulfonic estersand sulfones and mixtures thereof, wherein said hydrophobic compoundsare selected from the group of reaction products of castor oil withalkylene oxides, epoxidized fatty acid esters, low molecular weighthydroxy-functional polyolefins and oleochemical polyols based on aC₉-C₂₂-fatty acid and prepared by ring opening of epoxidizedtriglycerides, wherein the at least one further compound and/orderivative thereof is reactive toward and/or complexes with tertiaryamines.
 11. The polyisocyanate polyaddition product of claim 10 whereinsaid hydrophobic compounds each have at least two isocyanate reactivegroups.
 12. (canceled)
 13. A process for making a foamed polyisocyanatepolyaddition product comprising reacting: a) compounds which arereactive toward isocyanates, and b) isocyanates, in the presence of c)hydrophobic compounds selected from the group of reaction products ofcastor oil with alkylene oxides, epoxidized fatty acid esters, lowmolecular weight hydroxy-functional polyolefins and oleochemical polyolsbased on a C₉-C₂₂-fatty acid and prepared by ring opening of epoxidizedtriglycerides, d) at least one further compound, reactive toward primaryamines or capable of forming a derivative reactive toward primaryamines, selected from the group of cyclic sulfonic esters and sulfonesand mixtures thereof, and e) catalysts, blowing agents, and, optionally,auxiliaries and/or additives, to form a hydrophobic polyisocyanatepolyaddition product wherein said at least one further compound and/orderivative thereof is present in the product and is reactive towardprimary amines. 14-16. (Canceled)
 17. A polyisocyanate polyadditionproduct as claimed in claim 1, wherein said low molecular weighthydroxy-functional polyolefins have a molecular weight of from 500 to8000 g/mol.
 18. A method as claimed in claim 7, wherein said lowmolecular weight hydroxy-functional polyolefins have a molecular weightof from 500 to 8000 g/mol.
 19. A polyisocyanate polyaddition product asclaimed in claim 10, wherein said low molecular weighthydroxy-functional polyolefins have a molecular weight of from 500 to8000 g/mol.
 20. A process as claimed in claim 13, wherein said lowmolecular weight hydroxy-functional polyolefins have a molecular weightof from 500 to 8000 g/mol.